Basically if a peaked and tuned 29 lx would be safe to hook up to it
Umm , NO.
Some basic radio math. Even if it makes you're head hurt.
AM output = 4 x your carrier when 100% modulated.
So even if your 29 is just doing 4 watts then
4 x 4 = 16 watts
Where anywhere on the left graph is it possible to input 16 watts? I'm sure you can find a way ( I did) but , poof!
I'll include the first page just for reference.
These curves were produced by the tuned, single ended test circuit referenced above. This does not take into account bias currents and voltages or broad band transformer losses. Note also that the values on the graph are for a single transistor.
This doesn't mean that you can arbitrarily double the input for a pair of transistors. (actually yes it does but that is a further design element). It is however a good guideline.
In figure three the graph extends out to 16 volts but notice that the input curves are for 1, 1.75, and just 3.5 watts.
Even if figure two suggests that 5 watts input can be supplied to the device it only shows curves for 12 and 13.6 volts.
So in summary , Take your radio and plug it into a reliable watt meter and 100% modulate it into a dummy load. If that result is any more than approximately 8 watts you are approaching 1db compression (or well into it) and about to saturate the device.
8 divided by 4 is 2. 2 watts dead carrier is about all you can afford without turning the box into a grenade with a loose pin waiting for a place to happen.
I'll guess that a "tuned and peaked" 29 anything has not only in excess of 5 watts but all kinds of artifacts accompanying the signal as well. (okay I'm jaded and skeptical of any claim to "peak and tune" a radio by all but a qualified tech with all the tools). Again the answer is no, the 29 will smoke this 1970's amplifier design in short order. I'll take the under on this one as in less than 10 minutes.
I refer you to any number of members here for a "lick and stick" variable power modification. I don't have it on this laptop and won't go looking for it right now.
I don't know how many ways to tell you other than just NO. It will work but it's life expectancy would be minutes if not seconds.
Had enough?